io-multiplex/select.lisp

   1 ;; -*- Mode: Lisp; Syntax: ANSI-Common-Lisp -*-
   2
   3 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   4 ;   Copyright (C) 2006,2007 by Stelian Ionescu                            ;
   5 ;                                                                         ;
   6 ;   This program is free software; you can redistribute it and/or modify  ;
   7 ;   it under the terms of the GNU General Public License as published by  ;
   8 ;   the Free Software Foundation; either version 2 of the License, or     ;
   9 ;   (at your option) any later version.                                   ;
  10 ;                                                                         ;
  11 ;   This program is distributed in the hope that it will be useful,       ;
  12 ;   but WITHOUT ANY WARRANTY; without even the implied warranty of        ;
  13 ;   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         ;
  14 ;   GNU General Public License for more details.                          ;
  15 ;                                                                         ;
  16 ;   You should have received a copy of the GNU General Public License     ;
  17 ;   along with this program; if not, write to the                         ;
  18 ;   Free Software Foundation, Inc.,                                       ;
  19 ;   51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA              ;
  20 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  21
  22 (in-package :io.multiplex)
  23
  24 (defconstant +select-priority+ 3)
  25
  26
  27 (define-multiplexer select-multiplexer +select-priority+ (multiplexer)
  28   ((max-fd :initform 0
  29            :accessor max-fd-of)
  30    (read-fd-set :initform (allocate-fd-set)
  31                 :reader read-fd-set-of)
  32    (write-fd-set :initform (allocate-fd-set)
  33                  :reader write-fd-set-of)
  34    (except-fd-set :initform (allocate-fd-set)
  35                   :reader except-fd-set-of))
  36   (:default-initargs :fd-limit (1- et:fd-setsize)))
  37
  38
  39 (defun allocate-fd-set ()
  40   (et:fd-zero (foreign-alloc 'et:fd-set)))
  41
  42
  43 (defmethod print-object ((mux select-multiplexer) stream)
  44   (print-unreadable-object (mux stream :type nil :identity nil)
  45     (format stream "select(2) multiplexer")))
  46
  47
  48 (defmethod close-multiplexer progn ((mux select-multiplexer))
  49   (foreign-free (read-fd-set-of mux))
  50   (foreign-free (write-fd-set-of mux))
  51   (foreign-free (except-fd-set-of mux))
  52   (mapc #'(lambda (slot)
  53             (slot-makunbound mux slot))
  54         '(max-fd read-fd-set write-fd-set except-fd-set)))
  55
  56
  57 (defun find-max-fd (fd-set end)
  58   (loop :for i :downfrom end :to 0
  59      :do (when (et:fd-isset i fd-set)
  60            (return-from find-max-fd i)))
  61   ;; this means no fd <= end is set
  62   -1)
  63
  64
  65 (defun recalc-fd-masks (mux fd read write)
  66   (with-accessors ((rs read-fd-set-of) (ws write-fd-set-of)
  67                    (es except-fd-set-of) (max-fd max-fd-of)) mux
  68     (if read
  69         (progn
  70           (et:fd-set fd rs)
  71           (et:fd-set fd es))
  72         (progn
  73           (et:fd-clr fd rs)
  74           (et:fd-clr fd es)))
  75     (if write
  76         (et:fd-set fd ws)
  77         (et:fd-clr fd ws))
  78     (setf max-fd (max (find-max-fd rs fd)
  79                       (find-max-fd ws fd)))
  80     t))
  81
  82
  83 (defmethod monitor-fd ((mux select-multiplexer) fd-entry)
  84   (recalc-fd-masks mux (fd-entry-fd fd-entry)
  85                    (not (queue-empty-p (fd-entry-read-events fd-entry)))
  86                    (not (queue-empty-p (fd-entry-write-events fd-entry)))))
  87
  88
  89 (defmethod update-fd ((mux select-multiplexer) fd-entry)
  90   (recalc-fd-masks mux (fd-entry-fd fd-entry)
  91                    (not (queue-empty-p (fd-entry-read-events fd-entry)))
  92                    (not (queue-empty-p (fd-entry-write-events fd-entry)))))
  93
  94
  95 (defmethod unmonitor-fd ((mux select-multiplexer) fd-entry)
  96   (recalc-fd-masks mux (fd-entry-fd fd-entry) nil nil))
  97
  98
  99 (defmethod harvest-events ((mux select-multiplexer) timeout)
 100   (with-accessors ((rs read-fd-set-of) (ws write-fd-set-of)
 101                    (es except-fd-set-of) (max-fd max-fd-of)) mux
 102     ;; if there are no fds set and timeout is NULL
 103     ;; select() blocks forever
 104     (when (and (minusp max-fd)
 105                (null timeout))
 106       (warn "Non fds to monitor and no timeout set !")
 107       (return-from harvest-events nil))
 108
 109     (with-foreign-objects ((read-fds 'et:fd-set)
 110                            (write-fds 'et:fd-set)
 111                            (except-fds 'et:fd-set))
 112       (et:copy-fd-set rs read-fds)
 113       (et:copy-fd-set ws write-fds)
 114       (et:copy-fd-set es except-fds)
 115
 116       (handler-case
 117           (with-foreign-object (tv 'et:timeval)
 118             (when timeout
 119               (timeout->timeval timeout tv))
 120             (et:select (1+ max-fd)
 121                        read-fds
 122                        write-fds
 123                        except-fds
 124                        (if timeout tv (null-pointer))))
 125         (et:unix-error-badf (err)
 126           (declare (ignore err))
 127           (return-from harvest-events
 128             (harvest-select-fd-errors rs ws max-fd))))
 129
 130       (harvest-select-events max-fd read-fds write-fds except-fds))))
 131
 132
 133 (defun harvest-select-events (max-fd read-fds write-fds except-fds)
 134   (loop :for fd :upto max-fd
 135      :for event := () :then ()
 136      :when (or (et:fd-isset fd read-fds)
 137                (et:fd-isset fd except-fds)) :do (push :read event)
 138      :when (et:fd-isset fd write-fds) :do (push :write event)
 139      :when event :collect (list fd event)))
 140
 141
 142 ;; FIXME: I don't know whether on all *nix systems select()
 143 ;; returns EBADF only when a given FD present in some fd-set
 144 ;; is closed(as the POSIX docs say) or if some other kinds of
 145 ;; errors are reported too(as the Linux manpages seem to suggest)
 146 (defun fd-error-p (fd)
 147   (not (et:fd-open-p fd)))
 148
 149 (defun harvest-select-fd-errors (read-fds write-fds max-fd)
 150   (loop :for fd :upto max-fd
 151      :when (and (or (et:fd-isset fd read-fds)
 152                     (et:fd-isset fd write-fds))
 153                 (fd-error-p fd))
 154      :collect (cons fd :error)))